A few high-profile "sharing-economy" startups are gaining quick traction with users, including those that let consumers rent apartments and homes like Airbnb Inc., or get car rides, such as Uber Technologies Inc.

Both Airbnb and Uber are valued in the billions of dollars, a sign that investors believe the segment is hot—and a big reason why more entrepreneurs are embracing the business model.

At MassChallenge, a...

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